Recently, the preparation and distribution of promotional game cards, premium cards, lottery tickets and the like, containing hidden messages or symbols has become popular and widespread, in fundraising and product promotion. The recipient or user of such a card must remove from the card a layer of opaque coating material in order to reveal a number, message or symbol. A check number or security number may also be included on the document or ticket.
It would be desirable, for security reasons, to provide an article having hidden indicia that would provide an indication of whether the article has been exposed to various types of tampering or materials that potentially may be used for tampering in an effort to detect the hidden indicia or alter the article.
Modern technology gives the unauthorized person a number of techniques with which he may attempt an unauthorized detection of the hidden indicia or alteration of the article. A need exists to indicate tampering of the article from exposure to various solvents, glues, and elevated temperature.